File to Base36.

Base36 writes a number with the ten digits and the 26 letters, 0 to 9 then a to z, the same in either case. It is the biggest alphabet that is both alphanumeric and case-insensitive, which is why JavaScript's `toString(36)` and so many short ids use it. The tool treats the input bytes as one big number and writes that.

The bytes are read as one integer, big end first, and that integer is written in base 36 by repeated division. Each character carries about 5.17 bits, so the output is about 55% larger than the input. Leading zero bytes are kept as leading 0 characters. There is no padding.

URL shorteners, Reddit's post and comment ids, tracking and licence codes, database keys shown to people, and any place a counter has to become a short, case-insensitive string.

Yes: letters and digits only, nothing to escape, and the same string in either case.

It is for numbers and short ids. For arbitrary data it is slower than Base32 or Base64, because the whole input has to be divided as one number, and its 55% overhead sits between them. Base62 is shorter but case-sensitive; Base32 is streamable and padded.

No. Base36 is an encoding, not encryption: it changes how bytes are written, not who can read them, and anyone can decode it with no key. Encrypt first (AES, age, a library's sealed box) when the content needs protecting, then encode the ciphertext if it has to travel as text.

Drop the file onto the input or choose it with the button. Its bytes are encoded in your browser and the Base36 appears in the result pane, with the size it grew to. Copy it, or download it as a text file.

Base36 treats the whole input as one number, so the tool takes up to 512 KB at once; past that the conversion would stall the page.

Whatever needs the bytes as text: a short, case-insensitive id or a token that has to be typed. Base36 is safe in a URL as it is, and it is about 55% larger than the file, so it is for carrying bytes through text, not for storing them.

Nothing leaves your browser. The file is read into memory on your machine and the encoding is computed there, in plain JavaScript; the page makes no request with it. Load the page, go offline and it keeps working.

No. The "File to Base36" tool is free and opens without a sign-in, an account or an install.

Nothing. The "File to Base36" tool holds your input in the page's memory, so closing or reloading the tab clears it, and it saves nothing in this browser.

Any file the browser can open. The bytes are read in your browser and encoded as Base36; the result can be copied or downloaded as base36-encoded.txt. Base36 treats the input as one number, so the tool takes up to 512 KB at once.

Base36 output is about 1.55 characters per byte, and the status line under the result shows the bytes in, the characters out and the percentage. Base36 treats the input as one number, so the tool takes up to 512 KB at once.

Use the Base36 to file page: it decodes Base36 back to the original bytes, and names the download after the file type it recognises.

Yes, the same choices as the text encoder: Case, lowercase or uppercase.

Closest to the "File to Base36" tool: Base36 to file, Base36 encoder, Base36 decoder, File to Base62. Each opens on its own page, free and in the browser.

The "File to Base36" tool is one of 32 in its group. The group's page, /tools/encoding, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.